Ping_chilling

Reimplementation of the command ping in C.

Ping_chilling sends ICMP_ECHO / ICMP6_ECHO_REQUEST to network hosts. It is used to check if a host is alive. It is also used to measure the round-trip time (RTT) between a host and the source.
Ping_chilling is fully compatible with IPV4 and IPV6 adresses and handles DNS resolution.

Usage

Do make and then run :

sudo ./ft_ping [options] <destination>

You are requiered to run the program with sudo because the program uses raw sockets (SOCK_RAW with the socket function). We are aware that options such as SOCK_DGRAM exits but they don't seem to work with the function specified by the subject.

Or you can also use make run to run the program with the specified otions in the makefile.

The following options are handled by the program:

  -a                 use audible ping
  -c <count>         stop after <count> replies
  -D                 print timestamps
  -h                 print help and exit
  -i <interval>      seconds between sending each packet
  -q                 quiet output
  -t <ttl>           define time to live
  -v                 verbose output
  -V                 debug and verbose output
  -4                 use IPv4
  -6                 use IPv6

If you want to see what packets we send and what packets we receive, you can use the -V option:

As you may notice we do not send a iphdr / ip6_hdr structure since it is generated by the sendto function. Futhermore we can modify the TTL value of said structure using the IP_TTL / IPV6_UNICAST_HOPS socket option with the setsockopt function.

We also have a basic branch that you can look at if you want to understand how a basic ping packet is sent and received. It supports IPv4 and IPv6. However it lacks a lot of features and is only made for educational purposes.

Checksum

A Checksum is a digit representing the sum of the bits in a piece of stored or transmitted digital data, against which later comparisons can be made to detect errors in the data.

You can find many implementations of a checksum function in the RFC1017.
You do NOT need to calculate the checksum for the IPv6.
To calculate our checksum, we need to add the 16-bit of the packet together and reverse the result. We decided to make our own simple implementation of the checksum function, that you can find below:

unsigned short checksum(unsigned short *address, size_t len)
{
	unsigned short sum = 0;
	while (len -= sizeof(short))
		sum += *address++;
	return (~sum);
}

Docs

We heavily recommend reading the following headers files:

• <netinet/ip_icmp.h> (You can cast the ICMP6 header as an ICMP header)
• <netinet/ip.h>
• <netinet/ip6.h>
  
  
• RFC791 - Internet Protocol Specification
• RFC792 - Internet Control Message Protocol (ICMP)
• RFC1017 - Computing the Internet Checksum
• RFC3542 - Advanced Sockets Application Program Interface (API) for IPv6

MADE WITH LOVE BY :

alexandre-hallaine (ahallain)

Assxios (droge)